Ewen Callaway in Nature:
Is there anything CRISPR can’t do? Scientists have wielded the gene-editing tool to make scores of genetically modified organisms, as well as to track animal development, detect diseases and control pests. Now, they have found yet another application for it: using CRISPR to create smart materials that change their form on command. The shape-shifting materials could be used to deliver drugs, and to create sentinels for almost any biological signal, researchers report in Science on 22 August1. The study was led by James Collins, a bioengineer at the Massachusetts Institute of Technology in Cambridge.
Collins’ team worked with water-filled polymers that are held together by strands of DNA, known as DNA hydrogels. To alter the properties of these materials, Collins and his team turned to a form of CRISPR that uses a DNA-snipping enzyme called Cas12a. (The gene-editor CRISPR–Cas9 uses the Cas9 enzyme to snip a DNA sequence at the desired point.) The Cas12a enzyme can be programmed to recognize a specific DNA sequence. The enzyme cuts its target DNA strand, then severs single strands of DNA nearby. This property allowed the researchers to build a series of CRISPR-controlled hydrogels containing a target DNA sequence and single strands of DNA, which break up after Cas12a recognizes the target sequence in a stimulus. The break-up of the single DNA strands triggers the hydrogels to change shape or, in some cases, completely dissolve, releasing a payload (see ‘CRISPR-controlled gels’).